Leather processing



Feb. 19, 1935. e. M. ARGABRITE 1,992,133

LEATHER PROCESSING Filed Dec. 8, 1934 Patented Feb, 19, 1935 UNITED STATES:

PATIENT-OFFICE LEATHER PROCESSING George M. hrgabrite, Chicago, Ill. AppllcationDecember 8, 1934, Serial No. 756,582

5.0laims. 149-12) My invention relates to the processing of leather, and more specifically. to an improvement particularly useful inthe conditioning thereof to remove excess moisture after-the tanning operation proper is finished.

In the accompanying drawin the figure is a diagrammatic side elevation of a drying system.

After the tanning operation proper is completed on any kind of leather such, for instance, as a side, kip, or skin,'the leather is thoroughly impregnated with the liquor in which it has been soaking. Customarily a certain relatively large amount of this moisture is mechanically pressed out by serial tables or a drum setting out machine. In common practice the moisture left in the leather after this pressing operation is from to of the dry weight of the leather itself. This remaining moisture must be removed by drying. The art generally requires reduction of the moisture content in this way to about 6% or 8% of the weight of the leather.

This drying is accompanied by a hardening and a contraction of the material itself, and therefore such removal without wrinkling or excessive contraction presents a serious problem. One way to get the moisture out is to attach the skin or side to a fiat support or plate and ex ose the plate and leather both to heat in an atmosphere ca pable of taking. up moisture given off by the leather. For this purpose plates of composition board or plain paper board covered with lacquer or similar surfacing material have been employed as disclosed in United States Patent 1,118,813.

Such boards have a very short life, in the sense that the repeated use of them soon destroys their surface and necessitates replacement or repair. I am'also aware that supports of sheet metal covered with fibrous material with the fibrousmaterial lacquered have also been employed, as disclosed in U. S. Patent 1,808,306.

None of these plates of the prior art adheres to the leather, either with or without paste or glue to help them cling together, with suflicient efiectiveness to prevent considerable risk and occasional loss by the cleaving of the leather away from the plate. Particularly because the drying process dries the edges of the leather first, a common difficulty is to have a portion of the edge of the leather near the top cleave away from the plate a little. Then the weight of the portion already separated from the plate, combined with the drying and drawing action at the point where the paste still holds, rapidly extends this clear ing away until the weight of the detached portion is sufficient to tear the entire piece ofi the plate.

leather at all, the amount boiling water for Independent of the possibility of holding the of paste required to hold it is significant on account of the cost of the paste used, and still more so on account of the partial impregnation of the leather itself with the 5 paste.

According to my invention, I mount the leather directly on a sheet metal support having a higher degree of surface uniformity andrigidity than is possessed by .the previously employed.

As a specific instance or example of operation,

'plates of aluminum may be anodyzed for thirty minutes in twenty-five per cent sulphuric acid with a current density of twelve amperes per square foot, and then sealed by immersion in thirty minutes.

The leather is laid fiat against the 'plate and smoothed'out in firm contact therewith. I prefer in most instances to supplement the natural clinging action between the wet. leather and the plate, by applying adhesive.-

In the drying operation, the plate 10 with the leather 12 on it is then suspended, as by hooks 14, on a suitable conveyor 16 running on a track 17, and moved through a space or chamber into which the drying medium is blown, as from the orifices 18 of a duct 20.

It will be obvious that the specific preparation of the surface of the plate is given only for purposes of illustration. Satisfactory results may be obtained with a considerable variety of surface treatments generally according to United States Patent 1,946,147 of February 6, 1934. The specific procedure I have given is one with which I have secured good results.

One common difficulty with the prior art plates is referred to in the trade as puckering. This means irregularities shaped like blisters that develop irregularly in areas remote from the edges 40 of the leather. N0 difficulty of this sort develops with plates according to the invention. Without definitely stating that such is the case, I believe that the high thermal conductivity of the plates I employ causes the drying action to progress inward from the edge of the leather much more rapidly than would otherwise be the. case, and that this action has a bearing on the improved retextile or other fibrous surfaces 10,

The observed facts are that leather treated as herein set forth can be dried more quickly and evenly, adheres more firmly to the plate, suffers less reduction of area in drying, and in many instances comes 01f the plate with the grain surface that lay next the plate carrying a very attractive and finished appearance not obtainable with the prior art plates with which I have been familiar.

This application is a continuation in part of my copending application, Serial Number 708,236, filed January 25, 1934.

Without further elaboration, the foregoing will so fully explain my invention that others may, by applying knowledge current at the time of application, readily adapt the same for use under various conditions of service.

I claim:

1. Leather drying equipment comprising conveyor means, individual plate supports for individual pieces of leather, said leather pieces being adherently afiixed to the said plates, and said plates being supported on said conveyor means,

and drying means for acting on said pieces as they move on said conveyor; said equipment characterized by plate supports of anodyzed aluminum.

2. The method of drying leather which comprises adhering it directly to the surface of a plate of anodyzed aluminum.

3. A support for leather drying made of anodyzed aluminum, with the anodyzed surface naked and exposed for adhering leather directly thereto.

4. A support for leather drying, comprising a sheet-like metal body, Said body having a surface layer differing from the interior, said surface layer being of microscopic dimensions and of the order of magnitude of one-thousandth of an inch, said surface layer including a chemical compound of the metal itself formed in situ by chemical reaction with the metal of the body.

5. The step of treating leather which comprises adhering it directly to the surface of a plate of anodyzed aluminum and subjecting it to treatment while thus supported.

GEORGE M. ARGABRITE. 

